This invention relates to an elevator remote-control method wherein a program or data within an elevator control circuit is changed from a remote monitoring center by the use of a telephone circuit. More particularly, it relates to an elevator remote-control method which hinders a third party from intervening, thereby to attain an enhanced reliability.
FIG. 4 is a block diagram showing a conventional elevator control system which is described in, for example, the official gazette of Japanese Patent Application Laid-open No. 258382/1988. Referring to the figure, the elevator control system includes an elevator 1, an elevator control circuit 2 which drives and controls the elevator 1 in response to a hall call and a cage call, a remote monitoring center 3 which monitors the service state of the elevator 1, and a telephone circuit 4 which connects the elevator control circuit 2 and the remote monitoring center 3.
The elevator control circuit 2 is configured of a CPU 21, and a memory 22, an elevator interface 23 and a communication interface 24 which are respectively connected to the CPU 21 through a bus B. The elevator interface 23 is connected to the elevator 1, while the communication interface 24 is connected to the telephone circuit 4. On the other hand, the remote monitoring center 3 is configured of a computer 31, and a keyboard 32, a CRT 33 and a communication interface 34 which are respectively connected to the computer 31. The communication interface 34 is connected to the telephone circuit 4.
Now, an elevator remote-control method in the prior art will be described with reference to a flow chart in FIG. 5. By the way, control operations in FIG. 5 are executed by the CPU 21 which is included in the elevator control circuit 2.
First, for the purpose of causing the elevator control circuit 2 to run a maintenance control program, an operator in the remote monitoring center 3 inputs a maintenance command along with a secret code (key code) from the keyboard 32. On this occasion, the maintenance command contains various commands which express maintenance start, maintenance end, memory display, memory correction, etc. The key code is input only when the maintenance start command is input.
When the maintenance command is input to the elevator control circuit 2 through the telephone circuit 4, the CPU 21 ceases the run of an elevator control program and decodes the input command as interrupt processing (step S0).
If the decoded command is the maintenance start command, the CPU 21 decides whether or not the key code simultaneously input agrees with a key code previously set for the elevator control circuit 2 (step S1). Only when the key codes are in agreement, the CPU 21 runs a maintenance start program (step S2).
On the other hand, if the decoded input command is the maintenance end command, memory display command or memory correction command, the CPU 21 runs a maintenance end program (step S3), memory display program (step S4) or memory correction program (step S5), respectively.
With the elevator remote-control method in the prior art, as stated above, the maintenance control program is run if the key code which is input with the maintenance start command agrees. Therefore, the prior-art method has had the problem that, when the maintenance command and the key code have been known, a third party can refer to and change the programs or data held in the elevator control circuit 2, so the normal elevator control is hampered.